The present invention relates to footwear and, more particularly, to a footwear construction and the method for making the same.
In the footwear industry, there is an ongoing effort to produce footwear including a cushioning system that provides both energy return characteristics and a high level of comfort for wearers. The need to produce such a cushioning system is particularly pronounced in the design of work, walking and athletic footwear, where reduction of fatigue and increased cushioning are primary objectives. For example, to minimize the effects of standing for long periods on hard surfaces (e.g., concrete floors) and walking on such surfaces, it is desirable to provide footwear that cushions the wearer""s foot from the hard surface and also returns energy to the wearer during walking or running.
Conventionally, energy return and cushioning have been competing interests. Efforts to improve cushioning typically reduce energy return. One shoe sole assembly used to improve cushioning, disclosed in U.S. Pat. No. 5,233,767 to Kramer, includes multiple, hollow, uniform, vertical columns, which compress and bulge to provide shock absorption and, therefore, cushioning. Although the use of the uniform, vertical columns increases cushioning, energy return is sacrificed because the uniform, vertical columns may not rapidly snap back from the bulged shape after compression. In another footwear construction, disclosed in U.S. Pat. No. 6,131,310 to Fang, a flanged insole is positioned over an outsole including solid, cylindrical separating posts, but the insole is gapped a distance above each post. This structure increases cushioning due to the compression of the separating posts, however, energy return is lost because the columnar cylindrical posts may not rapidly snap back into pre-compression shape. Moreover, after the insole separates from the separating posts when weight is removed from the shoe, the separating posts cannot generate return energy to the insole due to the physical separation.
Although the cushioning systems of the prior art provide cushioning, there remains a long felt and unmet need for a footwear construction that provides a desired level of cushioning as well as energy return.
The aforementioned problems are overcome in the present invention which provides multiple, inverted, frusto-conical cushion cells disposed between an insole and midsole. The cushion cells are preferably mounted to or integral with the midsole. The insole preferably includes a rib extending around it to form a recess into which the midsole is nested to form an enclosed cushion system.
In a preferred embodiment, the rib of the insole is secured to an upper. An outsole shell, filled with polyurethane, is direct-attached to the insole and/or the upper. Preferably, the polyurethane exerts a pressure against the midsole, forcing the cushion cells firmly upward against the insole. The insole also may include multiple vent holes, each uniquely associated with one of the cushion cells to provide a vent for air to escape the cells during compression and enhance the shock-absorbing characteristic of the cells.
In another preferred embodiment, multiple cushion cells are positioned at the forefoot of the cushioning system and aligned with the metatarsal heel of a wearer. Another cushion cell is disposed under the heel of the cushioning system. This cushion cell is concentrically disposed in a vertical, cylindrical wall that extends from the midsole base.
The cushioning system of the present invention is preferably manufactured using the general steps of (a) securing an upper to an insole, the insole including an insole base formed in the shape of a foot and a rib that define a recess and (b) positioning a midsole in the recess where the midsole includes a midsole base and multiple upwardly opening, truncated cones integral with the midsole base, so that the largest diameter portion of the truncated cones abuts the insole base.
Footwear incorporating the cushioning system of the present invention is preferably manufactured using the general steps of (a) securing an upper to an insole where the insole includes an insole base and a rib that together define a recess; (b) positioning a midsole in the recess, the midsole including a wall extending from the midsole and multiple, hollow, inverted truncated cones and (c) securing a sole to at least one of the upper, the insole, and the midsole.
The present invention provides a unique footwear construction having a previously unachieved combination of cushioning and energy return. The interaction of the cushion cells sandwiched between the insole and midsole provide a unique structure that has the ability to both (1) compress and provide cushioning and (2) provide maximized energy return upon decompression of the cells. Furthermore, when the cushioning system is incorporated into a shoe and the filler material pre-loads the cushion cells, additional energy return is available from those cells because their upwardly opening walls are slightly pre-compressed.
These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiments and the drawings.